Hello.

I have the same problem with my Archer C50 AC1200 router as described in this old thread of another TP-Link model (LINK) which has been solved by a firmware update. My printer, which is connected to my home 2.4GHz Wi-Fi network, becomes unreachable after a few days and it doesn't matter which Wi-Fi device is trying to print. The current solution is to restart the router and the printer by powering them off and then on and then the printer becomes reachable over the Wi-Fi immediately. There must be a problem within the router, since I've never had a problem like this with the same printer but with a different router. The printer is connected directly to the router over the Wi-Fi and the connection is successful. This has been checked with the printer's connection report. I can also connect to the printer's settings by typing its IP address in the web browser, but this also stops working after a few days after restarting the router.

The router has the latest firmware version for my country, SPI firewall is enabled. I've also assigned the printer a static IP to see if the problem would be solved, but it didn't help because the printer has become unreachable again after a few days. So the printer currently has an IP address assigned in the DHCP Address Reservation which is the same as the IP address reported in the printer's connection report. However, the printer has never been visible in the DHCP Clients List.